The title comes from the Greek word apokaluptō , which means "an unveiling" or "a new beginning". Mel Gibson intended for the film to represent the cycle of civilizations—how every great empire has a beginning and an inevitable end.
If you are analyzing the film's structure or looking for specific scenes, here is the narrative index (timeline) of the movie: index of apocalypto 2006
The film ends with the arrival of Spanish ships. While visually striking, by the time the Spanish arrived in the 1500s, the great Mayan cities featured in the film had actually been in decline for centuries. The title comes from the Greek word apokaluptō